Front A/C vents issue

Hello guys, I got a new issue. My wife was complaining about the a/c not working last time she went on a long trip without me. When she got home everything was working fine, but I still took a look at the a/c. The only thing I found was the vacuum line had to be replaced, so I diet that. Also I add d some more freon, just to be on safe side. The truck was fine afterwards every time I drove it. Last weekend we drove to Rockport TX for a mini vacation. And about an hour on the road (btw we leave in San Antonio), it happened, front vents stopped blowing cold a/c on any settings. I can hear the blower but I can bearly feel some air coming out. So of course my wife started drilling a hole in my head lol. Anyway we pulled over a a gas station to take a "potty" break, when I started the truck afterwards the a/c was back to normal all the way to our destination. After 2 days of vacation driving home same thing happened after an hour of drive. Does anyone knows what the problem might be?
Sorry for such a long story guys, I just want to give as much detail as I can. Btw it is a 2003 Expedition 5.4L 2WD, and the a climate control is manual. Thanks in advance.

so you have the dial controls vs the EATC module? was the air flow coming out any other vent?

I am more familar with the EATC now as i worked through my "only out defrost vent" by o-ring replacement on EATC.

Even after that, I have now had the following occur twice:
While driving on a steady incline.... at base of mountains at small % incline for many miles before greater inclines.... that I had used cruise control and after a few minutes, the air moved from my panel to defrost vents.... but when I noticed and stopped (or shut off ac and back on) the air vents acted normal again. I have not had any other quirk occur since replacing my o-rings on the EATC's internal solenoids.

Yes it a dial control and no I didn't notice it going out from defrost. The middle row and the rear vents work fine when this happens, I thought I was the vaccum lines so I replace them, they looked old, but it didn't solve my problem

which vacuum lines did you replace?

IMO, for what it counts, if a line is broken or has a hole, chances are things will be in fail mode all the time, or near all the time. I found my EATC to have hte common issue of the O-Rings simply getting worn and my failure rate was nearly 100%, but after I got used to a few things about it, it worked out the front vents about 20% of the time and higher under lower RPM.

guess now wait for it to occur again and see if you can trace it while it is occurring, check all vents openings. being that the defrost is so far forward, you really cannot "feel" it on you when driving. I recommend to search for the diagrams for the HVAC system... may give some better clues and common issues. I probably had some links in my posts for my EATC fix which may include you tube videos on testing the vacuum on the AC vac reservoir and the vac check valve to the ac vac system, if your design is similar in that regard.

I changed the short hoses that connect in the T by the fire wall, it didn't fix my problem.

I have a very similar problem.

I will set the air settings so the air flows from the front and floor vents. Randomly it will change to just the defrost vents or floor vents only. Sometimes I can reset the air controls and sometimes I can not. Wife want a new car. I want to keep it. I have an EATC system.

Let me know if you found out how to fix it.

Thanks

Had the same problem. 04 eddie bauer expy. 5.4 AWD, all the bells n whistles.
It's NOT a vac line issue. A vac line will cause the air to come out the defrost. This is the electric motor that controls which vent it flows through. Can get stuck in the closed position and the airflow is like 10% of normal( what you are describing)
IF the dial system you have is NOT controlled by a cable then search for the motor and connector that directs the airflow. I reseated it(passenger side) and it started working properly again.
Have put on 400 miles since it occurred so i THINK it's fixed.
Probably jinxed myself haha.

Your's is intermittent so i would wager that the vent control kknob is actually not mechanical but electrical and sends the voltage to the vent select motor(i'm making up names here), you get the jist.

Thanks for your feedback. I will use it to troubleshoot my issue.

Hey guys, I'm sorry that I'm replying so late, I was very busy.
Thanks for the info josh, I don't know if that's my problem. The other day I went to the part store to get some replacement parts, and I also needed some new vaccum lines, then I saw a a/c check valve and I told myself, let me get one, why not, it's only $4. So when I got home I decided to just go ahead and replace mine. When I took the old one off I decided to compare it to the new one, it was an aftermarket one, but it don't matter. So I start blowing in the old one from all side, 2 side the air was traveling freely, the 3rd side at first freely and then kinda slower but it would stop, it would still go through but I had to blow really hard. This kinda sounds weird, I hope you guys won't make fun of me. Anyway, I took the new one and did the same test, first 2 side free air flow, 3rd side now air flow whatsoever, and immediately I thought to myself, that's probably my problem. If the new one has no airflow, it must the the right way, so of course I replaced them. So far I didn't have no problems with my a/c, but I didn't go on long trips yet. Next weekend I'm taking a 2 1/2 hour trip to the Gulf, this is when I usually have this problem, this will be my final test. I will let u know how it went.